An internal combustion engine with a fuel-metering system which includes a switching arrangement for generating metering signals responsive to a group of engine operating parameters, a compensation stage for accumulating and correcting said metering signals, a fuel metering means responsive to said metering signals, and a warm-up regulator for enriching the air-fuel mixture delivered to the engine during the warm-up phase is already known in the art. The known warm-up regulator affects the fuel enrichment solely as a function of engine temperature, that is, as part of the cumulative signal processing by the compensation stage. But, in a cold internal combustion engine not all fuel-air mixture injected into the intake manifold reaches the combustion chambers since a significant part of the metered fuel condenses and wets the inner walls of the fuel lines and engine. On the other hand, to have such an enrichment of the fuel over the entire engine operating conditions is unnecessary because the mixture losses due to the wetting of the walls remains substantially equal in magnitude when the load and speed are high. It is at these latter operating conditions that the warm-up enrichment factor as a total percentage of the proportional metering signal is small.
Thus, it becomes clear that it is advantageous to change the warm-up enrichment factor so as to be responsive to additional engine operating conditions rather than relying solely on engine temperature to compensate for the mixture losses when the internal combustion engine is cold.